1. THE SENSES
chapter 19

2. RECEPTORS
• -- Structures that detect stimuli. They
monitor both external and internal
environmental conditions. Conduct
information about those stimuli to the
central nervous system.

3. TYPES OF RECEPTORS
• Chemoreceptors- they detect • Mechanoreptors- respond to
chemicals. touch, pressure, vibration, &
stretch.
• Thermoreceptors- respond to
changes in temperature. • Baroreceptors- detect changes
in pressure within body
• Photoreceptors- detect structures.
changes in light intensity,
color, & movement. • Nocieptors- respond to pain
caused by either external or
internal stimuli.

4. THE TONGUE

5. • Gustation is our sense of taste. It
permits us to perceive the
characteristics of what we eat and
drink.
• Gustatory cells are taste receptors
housed in specialized sensory organs
termed taste buds on the tongue
surface.

6. • Detects five basic taste sensations: salty,
sweet, sour, bitter, & umami
• Facial Nerve - taste anterior 2/3 tongue
• Glossopharyngeal Nerve - taste
posterior 1/3 tongue

7. THE EYE

8. CONJUNCTIVA
• Stratified squamous epithelium
• Forms a continuous lining of the
external, anterior surface of the eye
• Contains numerous goblet cells which
lubricates and moistens the eye

9. FIBROUS TUNIC
• External layer of • Mostly formed by
the eye wall. touch sclera
• Composed of
anterior cornea &
posterior sclera.
• contains no blood
vessels

10. VASCULAR TUNIC
• Middle layer of the eye wall.
• also called “uvea” (grape)
• composed of three regions: choroid,
ciliary body, & iris

11. NERVES ASSOCIATED WITH THE EYE
• OPTIC
• OCULOMOTOR
• TROCHLEAR
• ABDUCENS

12. THE EAR

13. THE [[external]] EAR
• A Skin covered cartilaginous structure
called the auricle or pinna.
• The Auricle is funnel shaped and serves
to protect entry into the ear.
• Directs sounds waves into the bony
tube called the external acoustic
meatus.

14. MIDDLE EAR

15. THE [[middle]] EAR
• Contains an air filled tympanic cavity.
• Includes the the bones from lateral to
medial: Malleus, Incus, & Stapes.
• Responsible for amplifying sound
waves and transmitting them into the
inner ear.

16. INNER EAR

17. THE [[inner]] EAR
• Located within the petrous part of the
temporal bone.
• It includes the: vestibule, the semi
circular canals, & the cochlea.
• Mechanisms for equilibrium are located
within the inner ear.

18. Nerves Associated With Inner Ear
• VESTIBULOCOCHLEAR NERVE
& THE VAGUS NERVE

19. the process of hearing

20. • 1) sound waves are collected and funneled by the auricle of the
external ear.
• 2) the vibrations of the tympanic membrane causes movement by the
auditory ossicles.
• 3) pressure waves originate within the inner ear and travel through
the perilymph in the scala vestibuli.
• 4) high-frequency and upper medium frequency pressure waves in
the scala vestibuli cause the vestibular membrane to vibrate, resulting
in pressure wave formation in the endolymph of the cochlear duct.
• 5) the remaining pressure wave vibrations in the cochlear duct are
transmitted to the perilymph of the scala tympani and they exit the
inner ear at the round window.